The first step is setting up the projection, this can be done when creating the project, simply enter the name of the projection you are looking for and select it to save it, then create the project as usual. You can find the projection field on the advanced options.
Note that you can also set it up or modify it in the project's edition page, it is situated in the overall tab, below all the information you will find the current projection, you can select any other projection to replace it.
Once your projection is in place, you can open the viewer, once you are there, make sure to have the map displayed, once it is, click the minimap icon to display/hide the projection.
You can also check out the map in full screen, to do so, click the square icon situated right by the minimap one, click it again to bring the map back to its original size.
In case of any problem or difficulty, please do not hesitate to contact the platform's team.