Old HL1 TFC mod AVC -Using to practice and learn C++/C

Old HL1 TFC mod AVC -Using to practice and learn C++/C - Looking for help or others interested in adding to it..
I am hoping some of the seasoned vets here could help me get this on track I want to code in a sort of legal hack into the server DLL that works for admins only maybe a aimbot as well as some other random features ... really just want to see what is possible... it already has ENT manipulation which is incredible a great system for it really..
Here are some errors i need a hand with please!
https://i.postimg.cc/SJJG9VKn/avc1.png

https://i.postimg.cc/fJpffX3B/avc2png.png

https://i.postimg.cc/sBRPtr4W/avc3.png

https://i.postimg.cc/3yCjhctc/avc4.png