Well it really depends on the team. It varies greatly team to team. Each team will have a specific amount of their salary cap to spend on rookies and undrafted free agent pick ups.
Like for Detroit they had 11 picks but could only spend $5,551,658.
Whereas Washington had 3 picks and could spend $1,214,480
The rookie pool is, essentially, a cap within a cap. A team's rookie pool allocation is part of, not an addition to, the league's $75.1 million spending limit per team.