Okay, since EVERYONE seems to be having problems here like I did, I'll make it simple.
DON'T USE TWRP, it's outdated software we really don't need it unless you're making backups.
OP in thread obviously didn't have the same problems we did.
1. Download Recovery.IMG and ROM.zip from OP. Magisk.apk from their site.
2. Get phone into fastboot, at this point you should already have a backup made because beating the dynamic partition will eventually destroy your info anyway.
3. fastboot flash recovery RECOVERY.IMG from OP. Use volume buttons to go to recovery now.
4. From the new Android 11 recovery, factory data reset. Advanced boot into bootloader.
5. NOW fastboot boot RECOVERY.IMG, takes you into recovery directly and nails down the wiggly partition.
6. Update, ADB sideload ROM.ZIP
7. Reboot system. You now have Lineage.
8. From inside Lineage ROM boot into recovery again.
9. Update adb sideload MAGISK.APK, you don't rename it or anything, it'll give you a signature verification error on phone, go ahead anyway, magisk patches from outside ROM, runs code, reboot into system.
10. Install MAGISK.APK, follow directions. Direct install. ENJOY.
11. Now if you want GAPPS use Android 11 magiskgapps module.
DON'T TRY TO PATCH BOOT.IMG FROM OP: BOOTLOOP
DON'T TRY TO INSTALL NICKGAPPS, IT'S A FRUITLESS ENDEAVOR.
AS LONG AS YOU CAN ACCESS BOOTLOADER STILL FOLLOW THESE DIRECTIONS EXACTLY TO FIX YOUR FUDGE UPS, IT'S A SIMPLE SOLUTION TO WHAT YOU MADE INTO A COMPLICATED PROBLEM BY TRYING TO OUTTHINK THE SOFTWARE.
Thank you! I was able to install this rom fine, but rooting was another story. The tip to sideload magisk apk in LOS recovery was exactly what I needed!