Why a LinkedIn name is different
On most networks people pick a creative handle. On LinkedIn the name in your URL is read by recruiters, clients and colleagues, often on a CV or in an email signature, so it should look like you and nothing else.
Enter your first and last name in the keyword field and your field of work as the niche. The Clean style gives the most usable results, such as "jordan-lee", "jordan-lee-design" or "jordanlee-studio". The playful styles are there, but think twice before putting them on a CV.
When your name is taken
Common names are usually claimed already. Add something that tells people which Jordan Lee you are: your field ("jordan-lee-ux"), your city ("jordan-lee-london") or a middle initial. Each of these still looks deliberate when printed.
Avoid long strings of numbers. They make the address hard to read aloud and look like the default URL you were trying to replace.