The problem for any newcomer is understanding that there are not necessarily any quick fixes here, most installs have various things in them, not all are the same and even using the log I had to dump my main 4.12 install the other day, so much for years of doing this I could not fathom what had happened, WTF.
I have two 4.12 installs, one is a backup, that one was short of some things I had in my main install so I made sure all was well and then dumped the backup and replaced with the more up to date version, both working fine until a day or so later I made a static and the install crashed.
Knowing how gormless I am I assumed bad entry in the java or with the entries for the ini but the log kept going on about moving flags.
I had not touched them, done nothing with them, I looked high and low on the site and followed any previous issues reported for what was the western flag mod, tried everything before dumping the whole install.
The backup was copied into my SSD where I keep the main stuff and that stationary added, loaded up no problem, WTF.
It just shows that however long we have been at this we all can and do still fuck things up, me especially, I think the most likely thing is a inadvertent twitch of the mouse has moved a folder or maybe a click re-introduced something I sent to the bin, whatever the cause there was nothing I could do but use the backup and move on with whatever I was doing.
So if ponyboy314 is reading this take heart you are certainly not alone.
The insistence on the log will not in itself guarantee a successful outcome, however, it is a starting point for any of us trying to understand a problem and is used by all of us because we who have been here a long time know that in the majority of cases it is normally something easy to correct because it is usually a incorrect entry that will cause a CTD which is why here and at other modding sites it is the first port of call because essentially we are all using a mod activated game and each version number works in somewhat very similar ways.
As for the problem, unfortunately this pack also works for me in 4.12 so it is difficult to replicate the issues for ponyboy314 in order to give any meaningful help and solve the problem but we start with a log, always.
The mods here ponyboy314 have been used in many updated versions of the game, however, they do not necessarily work in all which is why besides the log we need to be clear exactly what install you have, here you have mentioned two!
So, where to go with this?
Check the thread itself and look for any similar problems and how they were fixed, or not.
Make sure you have any dependencies it specifies, and what game version recommended by the author, sadly he is no longer with us to ask.
What is a dependency you might ask?
DiFF FM, flight model, each game version has differences the mod helps overcome these in other versions, ie, 4.12 has changed considerably since 4.09
and the mod was intended to be dropped in the mods folder, different types you will come across:
MODS.
#SAS.
#DBW.
#WAW3, from B.A.T, a 4.12 mod pack, there is a different named one for each module.
Just some I can remember off hand, not sure for UP, is that a 4.09 modpack? I forget.
Some aircraft require another mod to function, not sure about these but some do not have their own cockpit and to work they will need the mod installed that has in order for things to work.
I could go on all day ponyboy314, wait untill you start making things for the game, then your head will really get messed up.
So, why is this old git waffling on? Because we have all been where you are, nothing gets fixed by throwing a hissy fit or shouting, things need to be worked through, sorry, sometimes there is no simple answer, patience and following instructions carefully is what gets results.
Apologies all for repeating most of what has been pointed out already, here and elswhere.
Take care and be safe.
Wishing you all the very best, Pete.