GNS3 is a PITA to configure and install. (but if you succeed it is handy and "fun").
Yes, you need either Virtualbox or VMWare (but for the latter the player would do), but if you have the GNS3 server running, you surely have one of the two installed and running.
Virtualbox has been more or less deprecated and VMWare was suggested.
But maybe you have the (underlying) QEMU not fully or properly set?
I have an (older) install on a Windows 7 (with Virtualbox) that was a nightmare (but for different reasons, the python changes).
I have an install on a Windows 10 that was a double/triple nightmare, there was no way to make it work with Virtualbox, it worked with VMware player at the nth attempt, after trying each and every setting (plus one) in both the GNS3 and in Windows network, and it still needs from time to time to disable/reenable the (stupid) VMware network adapters, or even uninstall and reinstall the player, and then if you change anything it will randomly fail to connect to the server, and sometimes (often) it needs lots of time to connect to the server, and the network settings inside the GNS3 running the Virtual Machine sometimes are not loaded, and a lot of other issues. (there is in practice no documentation for the initial setup/install part, there is the GNS3 Doctor which is a joke, and the forum is full of people with the same issues that noone knowledgeable answers to meaningfully, the answers are mostly magic spells or voodoo rites or similar - which BTW often work

).
In any case GNS3 won't do wireless Mikrotik (only wired) and those (old) templates with the catchy device names are the CHR renamed, or - if you prefer, you can only run the CHR in GNS3.