How to find your AncestryDNA Match Count using a desktop computer:
Step 1 - Go to https://www.ancestry.com and Login to your account
Step 2 - On the Ancestry homepage, Select DNA from the top menu bar, then Select DNA Matches from the dropdown menu
Step 3 - Make sure your window is expanded large enough to display all relevant information. In the image below, the window is too small to show to Ancestry's Filters. Right click the corner of the window and drag it away to enlarge the window.
In the image below, the screen has been enlarged and you can see the Filter by menu options.