Give enough substrate
A fossorial needs substantial depth; a terrestrial may still dig under cork or create a shallow chamber. Use substrate that can hold shape.
Do not refill the hole
If the burrow is stable, leave it. Filling it back in only makes the spider repeat the work.
Expect rearranging
Water dishes can be buried and plants or cork can be moved. Place heavy objects so excavation cannot make them collapse.
When digging signals a problem
Persistent wall climbing and refusal to touch the substrate is different from normal excavation. In that case check moisture, texture, enclosure height and recent disturbance.