Hi, I am someone who can not afford to buy server plans on websites, so makes them myself instead!
I am currently trying really hard to make a server with Create: Above and Beyond, and I am using the Server Pack from CurseForge on your main modpack page, I keep getting the same error "Incomplete set of tags received from server. Please contact server operator."
and I have no idea what to do, I have done multiple things, like making the server before starting, and then putting the "Server Pack" contents inside, or have just used the contents from the "Server Pack" to make the server itself, but no matter what I do, using the "Above & Beyond" modpack on my client, and the "Above & Beyond Server Pack" on the server side, please help!

Having the same issue! :/

I suspect you did similar things as I did.
I got forge-1.16.5-36.2.20-installer.jar to run successfully. I installed to the server modpack directory.

I wasn't sure how the server directory was supposed to look. I had tried to run forge-1.16.5-36.2.20.jar at some point - but it kept failing. Eventually I got minecraft_server.1.16.5.jar to run and so I thought everything was successful. I suspect this was running w/o the mods or something, and that's why the tags were all missing.

The server is not supposed to run in that manner, you must get the forge jar to run the server. A recent java update (jre-8u321) is incompatible with that jar, and that led to misleading errors and a crash.

I uninstalled java and downgraded to jre-8u301 (unfortunately this required registering an account with oracle) and that worked. Other jre's may work, but 321 is not compatible.

openjdk8_302 from adoptium worked great for me. it is at the bottom of my liked page