USB-to-Firewire adapter do not work and never have worked, as they are completely different protocols. Not sure why scammers are still selling these useless adapters. You will need a Thunderbolt 3 to Firewire adapter (https://www.apple.com/ca/shop/product/MD464LL/A/apple-thunderbolt-to-firewire-adapter) and a Firewire 400 to 800 cable. You can download the firewire driver from the Firebox support page (https://www.presonus.com/products/FireBox/downloads), but you might also want to try the latest firewire driver which can be found inside the installer DMG of any newer interface support page.
That said... I have been running a Firestudio 2626 and Firestudio Lightpipe for years but when I updated to macOS 12.3 they stopped working. Universal Control v1.7.6 (which is the last to work with the 2626) stopped working in macOS 10.14 or 10.15 (can't remember exactly when) but the interfaces still worked perfectly fine. They are now seen by macOS System Profiler but do not appear as audio interfaces. macOS 12.4 was supposed to fix firewire issues but it hasn't fixed things for me. Hopefully a future update will restore functionality. Others have reported Firewire functionality was restored with 12.4, so I can't say whether or not it'll work for you.
Hope that helps.
UPDATE: Last night I updated OpenCore Legacy Patcher to v0.4.8 (I'm running macOS 12.4 on a 2012 13" MacBook Pro) and did a fresh Build and Install OpenCore. After a restart, Post Install Root Patch, and PRAM Reset, both Firestudios are working again! I still need to connect them to my 2008 MacBook Pro to make changes to the I/O / monitor / clock setup, but the changes hold when connected to the newer laptop.