JaariAtmc

Don't zip the folder containing your modpack folders, zip the bin/config/mods folders directly.

This belongs in Platform Pagoda. If you are using Forge 2854/2855, you will have to use and rename the installer instead of the universal. Do not open the installer, rename it as-is.

Have you considered posting a log, just like the person in that old thread did?

This requires Universal Electricity as a mod as well, a version that's newer than the one included, which then causes more crashes due to mod incompatibilities with other mod versions, you could probably fix that as well by updating more mods, and at some point its no longer tekkit. These two mods were not meant to be added to TekkitMain.

The bug you show in your video is actually a slightly different one, but with a known cause: If you don't set a recommended java, but do set recommended RAM, you get that particular error.

That got me the warning screen instead, hence my confusion on the matter.

I can only get this to trigger the moment I go 1 MB above 16 GB (thus, 16385, 16384 gives the warning). Is this the same in your case, or are there other values that didn't work?

Had you gone and searched the issue, you would've found so many. With so many of my same answer. You used Forge 2855 universal. Don't. Either use 2855 installer renamed as-is to modpack.jar, or use 2847 universal, renamed to modpack.jar.

Out of interest, what's the required minimum memory for this modpack?

If they linked it to their microsoft account and that account is considered underaged, you can't use the launcher. Courtesy of microsoft, really. Such a pain.

Bugger off with your cracked launcher.

Yesterday, around that time, the Xbox service that handles microsoft account logins was down for some time. We had a couple reports in our discord, and Minecraft's own discord nearly got spammed to death about it.

How are you starting your server?

That's because of the M1, not because of the modpack.

Which modpack? Also, pretty likely that your school's network is just outright blocking that download. Kinda surprised it even let you use/download this launcher.