Player's Handbook, 5th Ed., Wizard Class Features:
Copying a Spell into the Book.
[...]
For each level of the spell, the process takes 2 hours and costs 50 gp. The cost represents material components you expend as you experiment with the spell to master it, as well as the fine inks you need to record it. Once you have spent this time and money, you can prepare the spell just like your other spells.
I haven't seen a rule that would make it free to copy from a scroll. Your quote is just another obstacle when trying to copy a spell.