If your using Chrome or Firefox
Simply open the Studio via our managed package in Salesforce. Note that the fullscreen option won't work.
If your using Edge or Internet explorer
For technical reason, our studio cannot connect to Salesforce sandboxes when you use Edge or Internet Explorer, because they have an extra layer of protection at browser level. Unfortunately we are dependent on Salesforce concerning that problem and we can't solve it by our own means.
Fell free to contact us for more details about this issue.