Find the recently installed ONLYOFFICE Enterprise in My Apps and click the 
button to enter the app settings section.
Then open File Manager access the app's file system, edit the /app/data/config/production-linux.json file and change the default secret to your own unique secret key.
"secret": {
"inbox": {
"string": "mysecret"
},
"outbox": {
"string": "mysecret"
}
Where mysecret is your new secret key used to sign the data. It is the secret to validate the JSON web token in the request to ONLYOFFICE Docs.
Note: be sure to change the two secrets above to the same unique password.
Next, you need to add a license key. Place the license.lic file to the following application folder:
/app/data/license.lic
Restart the ONLYOFFICE Enterprise app to pick up the license and update the secret key.