failed install on brand new virtual ubuntu

[StarWing01]

I'm installing new instances on a brand new, virgin-virtual ubuntu (ubuntu-22.04.3-live-server-amd64.iso)
When trying to install radarr/prowlarr/... the script stops with the error:
(https://wiki.servarr.com/install-script)

Installation files downloaded and extracted
Removing existing installation
Installing...
mv: cannot stat 'Prowlarr': No such file or directory

I already used this script on another machine, and this did work. To test, I've downloaded a new iso from ubuntu and immediately tried the script after the ubuntu install (without changing/updating anything), but failed with the same error.
I'm running the script as "sudo".

 lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 22.04.3 LTS
Release:        22.04
Codename:       jammy

[StarWing01]

f**k, if I run the script from / instead of /opt, then it works, after having a look in the script..
Lost 2h on this :)