A wall route can be planned near a freestanding tree, but the two items must each be suitable and securely installed in their own right. Check the tree's position, stability, anchoring requirements and platform limits before treating it as an access point.
Do not physically join the structures with an improvised bridge unless the relevant manufacturers approve that connection. Consider how the cat will move between them and whether a jump could push the tower out of position. Measure the usable landing areas rather than the distance between decorative edges. Also think about future movement: if the tower is shifted for cleaning, the wall route may temporarily lose its safe return path. Keep the arrangement consistent and block access when essential components are moved. A coordinated layout needs more planning than simply placing two products close together.
Draw the tree's position on the floor plan and note that it is part of the route. Anyone moving it for cleaning should know that the wall shelves may need to be kept inaccessible until the original arrangement is restored.
For product comparisons alongside this advice, see SkyRoute wall climbing set and Feline Sovereign Spire. The details below explain their sizes and uses.
Further reading: vcahospitals.com; cats.org.uk.
SkyRoute wall climbing set
Feline Sovereign Spire