First you will need to connect your SQL database to the portal.
Run the following command to do that changing the parameters in brackets for the actual data:
mysql -u [uname] -p [pass] [db_to_restore] < [backupfile.sql]
After that copy the data from the
c:\Program Files\Ascensio System SIA\ONLYOFFICE\Data\ folder to the corresponding
/var/www/onlyoffice/Data Linux folder. In case you want to transfer the configuration files completely from Windows to Linux, copy all the files you saved from the
c:\Program Files\Ascensio System SIA\ONLYOFFICE\WebStudio\ folder to the corresponding
/var/www/onlyoffice/WebStudio folder, or choose which files need to be copied.