Because I have received this question for like the hundredth time, and thought I would dedicate an entire post answering the question, "does this mean we're not allowed to write outside our ethnicity?"
Well.
In order to do so, you need to file an application for a License to Multicultural Writing with your local Department of Multiculturalism. This department is either provincial or federal, depending on your country. Canada and the US, sharing very similar multicultural histories, share the same department which is on federal level, several branches across the two countries.
You will need to first fill out the MC-01 form, which is a general license form. (The fee for this general license is USD$50.) Then you need to fill out MC-1837 (which is specifically the license for Steampunk: Multicultural). If you are creating a steampunk work specifically about non-white peoples, you will need MC-3100(BC). YOU MUST FILL OUT AND SUBMIT BOTH FORMS TOGETHER. Failure to do so will result in unnecessarily prolonged processing.
Licensing for each multicultural work you aim to produce depends on the region you write about; check with your countries' department on the rate. As a general rule, rates will depend on how long your country has been involved with said country; the longer your country has colonized this particular culture, the cheaper the licenses will be. However, if you are of Western European descent, these rates can often be forgiven and you will get a 75% discount.
Processing will take at least 6 months, and it goes through several committees of People of Colour and Ethnic Representatives from the culture you are applying to write about. 90% of the time you will be asked to produce samples of the work you seek licensing for, especially if you are a new media creator. Approval is not guaranteed. It may be years before you are finally approved. Please be patient as there are many applicants to be processed--up to 100 million a year!
In the United States, if your work is egregiously racist, you will be impounded for a fine of $50 - $50,000, to be determined by a Jury of Disapproving Negros. They may also involve representatives of NMNAs (Non-Mascot Native Americans). If your work features poverty porn of Africa, Side-Eyeing African Children will be allowed to take arbitrary votes on the extent of your fine. If your work features cultures of East Asian extract, Inscrutable Orientals, from Section YP-1882, will place final call on the result of your work.
These are only a few sections of the entire Department of Multiculturalism division that processes these applications. If a certain section is not available close to you, your application will be forwarded to another branch that has the relevant Ethnic Representatives. To save yourself time, research where the Ethnic Representatives relevant to your work are before applying, and submit your application to that particular branch.
You get the idea. Now go write. And don't quit your day job.