Hi Sileka, sorry for the issue! This is due to a bug in an older version of StimuWrite. On open, the app checks the itchio server once to see if there is a new version and is supposed to notify the user if there is an update. There was bug in some older versions of the app that crashes it once I changed my username on itchio. StimuWrite does not send or receive any data other than this one time check.
If you update the app to the latest version you will be able to use it offline. I recommend downloading and running StimuWrite through the itchio app, as it will keep it automatically up to date with the latest fixes and features. Happy writing!