have a look at https://docs.mendix.com/refguide/system-requirements#2-1-tortoisesvn
This will tell you which version to download. After installing, reboot PC or it might not work.
After that you can right-click on your project directory folder, and select the "Edit conflicts” or the "SVN Resolved” this will show you what is conflicted and you can solve it.
In the settings of Tortoise you can select which you want to see, when right clicking any folder.