Composer installation error

[neolium]

Describe the bug
Installation not possible.

To Reproduce
Steps to reproduce the behavior:

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
No error and clean install :-)

Screenshots
None, just the error:
[RuntimeException]
Failed to clone https://github.com/tomlegkov/encryptable-fields.git via https, ssh protocols, aborting.

• https://github.com/tomlegkov/encryptable-fields.git
  Cloning into '/var/www/html/lynnhosting/vendor/tomlegkov/encryptable-fields'...
  remote: Repository not found.
  fatal: repository 'https://github.com/tomlegkov/encryptable-fields.git/' not found

• git@github.com:tomlegkov/encryptable-fields.git
  Cloning into '/var/www/html/lynnhosting/vendor/tomlegkov/encryptable-fields'...
  git@github.com: Permission denied (publickey).
  fatal: Could not read from remote repository.

  Please make sure you have the correct access rights
  and the repository exists.

Additional context
I tried to install the panel and then to try it out. Tried installing everything w/ composer but he asks for credentials (see the log on the top).

Best regards
neo