Guys this isn't complicated. Canis is right in everything he said (thx Canis) but might be more effective just to walk through everything step by step.
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Anyway for Jakey's specific question, the key point is that there are two drawings. Two completely separate drawings, one for 1OA and the other for 2OA. That NHL table is talking about only the 1st drawing (ie chance of picking 1OA).
If Ottawa wins the 1st one, like you said they jump 10 spots and are guaranteed to pick #2 (and ANA picks 1). But, if a team with a better draft position than Ottawa wins the first drawing then THAT team picks 1OA and the other drawing takes place for #2 (which could still go OTT's way). Either way after the first drawing the teams are re-seeded so that the same team can't win both drawings.
Anyway the difference in % is because If Ottawa doesn't win the first lottery, they're absolutely in the mix for the second overall pick. If they win THAT draw, in vast majority of cases they will jump 10 spots and then pick #2. There are a few edge cases that Canis rightly mentioned but the reason OTT has a 5.4% chance of picking 2-4 is because there is a drawing for the first pick and a separate drawing for the second pick.
There are some edge cases which have to do with the fact no team can jump more than ten spots in either drawing. So if a team with a worse draft position than OTT wins the first drawing then OTT drops a spot during the re-seeding -- so then the highest they could go is 3. But if BUF wins the lottery then BUF is locked into 3 so if OTT wins the 2nd drawing they'd ordinarily jump 10 spots to 3, but if BUF wins that first drawing they've already locked up #3 so OTT would slide to 4.
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TLDR: 2 drawings, one for 1OA and the other (likely) for 2OA. 2.5% chance Ottawa wins the first, 5.4% total chance Ottawa wins either the first or the second, that 5.4% includes all of the edge cases in prior paragraph. Either way 94.6% chance Ott does NOT win the lottery which would mean we get their pick this year (most likely 12OA)