Pope Francis recently approved a change to Catholic translations, making this "do not let us fall into temptation". The text literally says "do not lead us", with no ambiguity or even a hint of "fall". The word translated "temptation" here, however, is the Greek word translated "trial" in James 1:12, not the word translated "temptation" in James 1:13 and elsewhere. When we are actually letting God lead us, he always "provides a way of escape". 1 Corinthians 10:13 It is when "we like sheep have gone astray" (Isaiah 53:6) that we "fall into temptation".1 Timothy 6:9
"the evil one" - literally "the evil". The same Greek phrase is used many other places, e.g. Matthew 5:37, John 17:15, 2 Thessalonians 3:3, 1 John 5:18. It is a definite article, it is either a definite but impersonal evil like the the Evil in "A Wrinkle in Time", or an evil person. In my uncredentialed opinion, translations (including the venerable King James) with just "evil" are just wrong.