A few things.
I don’t know how much stock you put in the Chamber of Commerce generally but they are effectively a lobbying group not a think tank.
They are talking about LEGAL immigration, the kind where WE can control the spigot. We can decide the general composition of the immigrants coming into the country to match our needs.
The entire paragraph you quote depends on the immigrants filling bottlenecks that allow current residents to be more productive by leveraging the cheap labor of the immigrants in places where there isn’t enough cheap labor. But even this is probably bullshit for our country. If we were a country full of doctors but no nurses so that doctors ended up doing a lot of the nursing work, then sure, we should import more nurses, but that’s not what illegal immigration does (and it would still depress the salaries of nurses). If we were a country full of lawyers but no secretaries or paralegals so lawyers ended up doing a lot of secretarial work, then sure but again, that is not what we are talking about. How does all the illegal labor in the construction business allow current construction workers to leverage themselves and be more productive?
The pdf you cite seems to think illegal immigration (the kind over which the country does NOT have the ability to determine the qualities that we are letting in). It only mentions illegal immigration once but it implies that reducing illegal immigration is a good thing.