The installer of GDLauncher will ask if you want to do manual or automatic setup of Java, please click on automatic as it’ll set everyhting for you.
Download GDLauncher;
Create a folder close to the root of your hard-drive (to avoid “Path is too long…” error), for e.g. “C:\GDLauncher” or something similar;
Open GDLauncher, go to the settings tab (little cogwheel);
General -> Scroll to the bottom and look for “User Data Path” Then set the path to “C:\GDLauncher” (same path you wrote before) and check “Copy current data to the new directory”;
Java -> Click on Java on the left side. Set desired Java Memory (RAM Allocation) for at least 4096 MB, even tho I’d recommend going with 6384 or 8192, but that totally depends on how much RAM you have available.
Restart the launcher
To add modpacks or specific versions, click the + in the lower left corner and select what version you want (or modpack). You can select from Snapshots to Modpacks or even create your own Forge of Fabric instance and add your own mods.
If you run into any issues, you can join my discord server so I can try to help you.