...
The provided link must be similar to:
Integration test environment: https://staging.must.digital/signstash/en/home?partner=[PARTNER_CODE]
Production environment: https://msignstash.multicert.com/signstash/en/home?partner=[PARTNER_CODE]
Where the placeholder [PARTNER_CODE] must be replaced with your partner code.
Example: https://staging.must.digital/signstash/en/home?partner=PRT.102102102102102
...