The "unexpected error" you encountered is not a bug in the add-on, but was triggered by the extremely strict automated security systems (firewalls and scanners) of the XenForo Cloud servers, which are much more restrictive than traditional hosting environments.
The original 1.8.6 .zip package included the composer.json and composer.lock configuration files (which we used to natively integrate the geolocation library). The XenForo Cloud scanners, detecting these dependency configuration files, preemptively block the installation, generating a "false positive."
We have just updated and replaced the 1.8.6 release .zip file (the version number remains the same, but the package has been optimized for the Cloud). We removed the unnecessary configuration files (leaving only the pre-compiled libraries inside) and optimized some code to easily pass the automated security checks.
Please re-download the .zip archive and try the installation again. It should now proceed smoothly and without any hitches.
Let us know if the installation goes through successfully or if you need any further assistance