crisscross here means what?

In this sentence, "crisscross" means to go to many different places around the world. In your mind, imagine a globe, and many places around the world where there are conferences. Then imagine a line drawn between one place and another. If there were a lot of conferences, the lines would "crisscross".

Imagine how to weave....

So just like their trails crisscross?

Exactly

"Crossing" the ocean is descriptive, but a little humdrum.

"Crisscrossing" suggests going here and there; hither and thither; bustling back and forth and roundabout.

"Crisscrossing" makes business travel sound very important and time consuming.