Open gitlab config file in an editor
Search for the following line
#gitlab_rails['lfs_enabled'] = false
Uncomment it and change the value to true. It will look like this:
gitlab_rails['lfs_enabled'] = true
Save the file and reconfigure GitLab for the changes to take effect.
This will enable Large File System in your GitLab.
The default file size limit is 250 MB. If you want to increase it, open the config file and change value to the number you want and reconfigure GitLab.
nginx['client_max_body_size'] = "200m"