This is how to get the 6th tape! (Ik this is super late but still gonna make this guide for my friends)

Sadly i tried seeing if you could get it any other way, but it seems you seriously just have to hack in it to get the tape. The good news is, you dont have to install NOTHING.

Step 1: Go to your files and type on the search bar %appdata% and press enter.
Step 2: On the search bar, click the AppData. 3 folders will appear.
Step 3: Click on the folder called LocalLow. Then click on the one called MangledMaw.
Step 4: Once you click on MangledMaw, click on Amanda the Adventurer. Then click on save.sav
step 5: Open save.sav in Notepad and look for the words SecretTapesUnlocked (it will show the number of tapes you have gotten). Replace the number next to the ( : ) with 6.
Step 6: Save and restart the game. Now once you load back in, the tape should all be there.

Thats it for the guide! This trick could also work on getting an achievement that you cant seem to get or etc.