Park Matilo is open to the public and can be entered at virtually any time of day at no cost. There are various signs scattered in and around the park with information about the Roman fort, as well as evidence from later times. It is located outside of the centre of town. You can get there from Central Station or the train station at Lammenschans by bus. You can also walk to the site, but it will take you about 30 minutes from Lammenschans (and longer from Central Station).
The park has a website, but it’s only available in Dutch.