I have eMClient connected to Fastmail Mail, Calendar, & Contacts. However, I am having some problems. How do I get my contact groups to download from Fastmail? How do I download my Fastmail aliases and identities? Where is the Compose button?
Fastmail have instruction on their website about setting up eM Client with their services. Check that out and see if it helps.
The compose button in eM Client is the New button in the top left.
Clicking the down arrow next to New offers other options.