From below.
https://media.deltafaucet.com/MandI/107607 Rev B.pdf
Install end valves (5), spout adapter (6) and spray support assembly (9) from below. NOTE: Hot side end valve is labeled (8). Replace washers (3) on end valves and spout adapter, rotate 90˚ to expose screws (1). Replace nest (4) on spray support assembly and rotate 90° to expose screws (1).
Tighten screws (1) with a regular slotted screwdriver. NOTE: One screw can be fully tightened before the other screw is tightened.
Make sure end valves are properly aligned (10) with corrugated tubes to spout and nest angled toward tub. Carefully bend corrugated outlet tubes (11) and insert into tee (12). Connect tee to spout adapter (6). Connect inlet tubes (13) to water supplies. Be careful bending the copper tubes. Kinked tubes will void warranty.