An ultimatum "convert or die" does not exist in the actual document. Its actually "deport or die."
Also it is notable that they were to be unmolested in deportation and disposition.
And so that the said Jews and Jewesses during the stated period of time until the end of the said month of July may be better able to dispose of themselves, and their possession, and their estates, for the present we take and receive them under our Security, protection, and royal safeguard, and we secure to them and to their possessions that for the duration of the said time until the said last day of the said month of July they may travel and be safe, they may enter, sell, trade, and alienate all their movable and rooted possessions and dispose of them freely and at their will, and that during the said time, no one shall harm them, nor injure them, no wrong shall be done to them against justice, in their persons or in their possessions, under the penalty which falls on and is incurred by those who violate the royal safeguard. And we likewise give license and faculty to those said Jews and Jewesses that they be able to export their goods and estates out of these our said kingdoms and lordships by sea or land as long as they do not export gold or silver or coined money or other things prohibited by the laws of our kingdoms, excepting merchandise and things that are not prohibited.
There was not a forced conversion program.
If you stayed, you had to be converted or die.
If you went, you could stay Jewish.
It’s that simple.