Hi! Bom caminho!
Your location, as listed, is a bit confusing. Muge is one town, and Salvaterra de Magos is another, both within Santarem district. (To add confusion, Santarem is a big city in its own right; the capital for the district of Santarem.) Santarem is a significant city on the caminho, and you could go on from there.
You would have to get across to the other side of the Tejo (Tagus) to reach Santarem. Rome2Rio is probably your best bet for finding a way of doing that. I've referenced the Muge>Santarem route.
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Looks like there's a bus you could catch, very easily. The #901!