For anyone who has already partitioned their Nexus 7 prior to trying to flash this ROM. If you run into installation errors because the partition is too small, I will list the steps I took to get everything installed.

Here are the files you will need (or at least what I used and worked for me):
1) sysrepartundo.zip found here
2) REPIT: for Nexus 7
3) Latest Magisk apk
4) Latest ROM, GAPPS (I chose pico), Kernel (optional), TWRP. Which are all found in the OP Google Drive link.


Next we will need to partition the device in order to install everything smoothly:
1) Boot into bootloader and flash TWRP. I used the one from the OP Google Drive folder.
2) You will have to reformat your partition to it's original state before using REPIT. So install sysrepartundo.zip after it's done, restart recovery.
3) Follow the installation instructions for REPIT linked above. Or just read this excerpt from that thread (except step 6).
*I had some issues with it installing initially. Restarting Recovery and following the steps closely seemed to work for me.

If you already have a ROM installed, repit will backup, change the partition, restore and resize.
- You can just reboot once the script finishes.

1. Boot into TWRP
   • Swipe to Allow Modifications
2. Copy the repit zip to /tmp
3. Disconnect from computer
4. Disable MTP
   • Disable MTP TWRP -> Mount
5. Install repit
   • TWRP -> Install -> navigate to /tmp and flash the repit zip
6. Reboot to system

Click to expand...

4) Once it's partitioned to the larger size you shouldn't have any issues following the directions from the OP.
*For Magisk: Once you download the latest apk, change the file extension from .apk to .zip and install as per instructions below.
**For Kernel: I installed it after step 5 because I forgot to install it after the ROM. This is optional and can be installed at any point after the ROM is installed.

Installation:
1.) Do factory reset in TWRP - keep internal storage this way.
2.) Format /system partition in TWRP
3.) Install ROM
4.) Install Gapps (optional)
5.) Install Magisk 23.0 / 24.1 (optional)
6.) Reboot into system and start to setup your device.

I will also add that some installation instructions from this post helped. So I'll include that bit below.

Dont' make installation queue in TWRP !
Install each zip file manually.

For gapps installation it helps if you mount system partition manually in TWRP mount menu - before gapps installation.
if mounted already in mount menu - unmount and remount again.

I hope this helps someone. I spent like 2hrs trying to figure out why it wasn't flashing even though my system was already partitioned. And after the fact, I overlooked the part about the partition in the OP because I figured mine was already good. My mistake