You will probably need to install TortoiseSVN or SmartSVN. TortoiseSVN 1.7.15 is for Mendix 7 and below, SmartSVN for Mendix 8.
https://docs.mendix.com/howto/collaboration-requirements-management/troubleshoot-version-control-issues
This does mean going into your project directory using Windows Explorer and resolving by right clicking over the affected files.
Hope this helps.