No more 256 error! I figured it out.
Here's my exact steps.
Before continuing, delete Lutris and PSOBB if it's been downloaded.
(If you use Lutris for a bunch of other games, backup your settings if possible, IDK I don't use Lutris outside of this)
1. Downloaded Lutris from Discover.
2. Launched Lutris, waited for all downloads to complete (look on left side in Lutris, you will see download progress bars)
3. Open the Preferences menu in Lutris (upper right hamburger menu)
4. Go to Updates tab
5. Click the button to download wine-GE, wait for completion
6. Click on the button below that "Check for Updates", wait for completion
7. Click the button at the bottom "Download Missing Media", this should say "No new media found"
8. Go to the Lutris webpage and download the install script (see attached image)
9. EDIT the script, you can just double click it and it will open with Kate.
10. Look for [{"ephineapsobb":"
http://files.pioneer2.net/Ephinea_PSOBB_Installer.exe"}
11. Change the URL so it's https:// (see attached image) and SAVE the file
12. Back in Lutris, click the + in the upper left corner and "Install from a local install script"
13. Browse to the script you just modified and saved, click through the rest of the installer and approve any Mono/Gecko installers.
That's it!