Well, your first step is to unzip the folders you have so that you may ascertain exactly what you are working with. There are questions that need answers.
For example, what version of RoboHelp was used to create these projects?
Assuming your plan is to continue using RoboHelp 2019, you will likely find you need to use RoboHelp 2019 Classic to continue the project as 2019 is totally new and won't be feature complete until some time next year.
If you have never used RoboHelp before, you should consider some training to help you get up to speed on it.