You have wrote that:
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I am copying exactly what the email said. I was able to change them to only:
ns1.linuxserver29.com
ns2.linuxserver29.com
but I cannot enter the IP address after that. Am I doing something wrong? Please help!!
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You have need to change them either by IP address or by name only. You have to just enter like:

ns1.linuxserver29.com
ns2.linuxserver29.com
OR
67.15.230.108
67.15.230.109

Hope this will resolve you issue.