She digs out her badge and pins it to her robes. The looks dial down a lot after that.
The Guild's front is an expansive lobby-like area, like a bank or a government office. There's couches and bulletin boards to one side. The greeter asks their business, then directs them to the appropriate line for new registrations. Abyssia splits off to go sell her spider parts, and says she'll be in the cafe across the street.
Apparently registering as an E-rank adventurer involves a fee of three silver coins, monthly dues of five silver coins, and then they take 1/3 of all loot earned in a dungeon. This is used to upkeep the Guild's services as a centralized broker for goods and work, to serve as insurance against security risks and untimely deaths (they pay out quite a lot for deaths of registered Adventurers, to whoever is listed for them, no you can't waive this), and to pay Crown and city taxes.