Prosody already existing certificate installation error

Hello,
I am having a problem installing jitsi meet because of an installation error with prosody.

Because I already own an certificate for the jitsi subdomThis text will be blurredain I choose the second certificate option during install and point to the existing letsencrypt certificate
First question: The certificates are pem files, but the default certificates names in the dialoge end with .key and .crt. Can Jitsi handle also pem certificate or do I need to convert them?

If jitsi is behind a nginx manually already configured with these certificates, can I leave the configuration during jitsi install empty ?
At the moment I am choosing the second option for my own certificates and point to the certificates but getting the following symlink error.

But the referenced file in the error is not the file I referenced to in the dialogue.
To ensure that it is not a permission problem, I set temporarily the key file to 777 permission

I am getting the following error
`Setting up jitsi-meet-prosody (1.0.4466-1) …
grep: /etc/prosody/prosody.cfg.lua: No such file or directory
grep: /etc/prosody/prosody.cfg.lua: No such file or directory
Generating RSA private key, 2048 bit long modulus (2 primes)
…+++++
…+++++
e is 65537 (0x010001)
Choose key size (2048): Key written to /var/lib/prosody/meet.mydomain.com.key
Please provide details to include in the certificate config file.
Leave the field empty to use the default value or ‘.’ to exclude the field.
countryName (GB): localityName (The Internet): organizationName (Your Organisation): organizationalUnitName (XMPP Department): commonName (meet.mydomain.com):
emailAddress (xmpp@meet.mydomain.com):
Config written to /var/lib/prosody/meet.mydomain.com.cnf
Certificate written to /var/lib/prosody/meet.mydomain.com.crt

ln: failed to create symbolic link ‘/etc/prosody/certs/meet.mydomain.com.key’: No such file or directory
dpkg: error processing package jitsi-meet-prosody (–configure):
installed jitsi-meet-prosody package post-installation script subprocess returned error exit status 1`